Cube

A cube is a solid box whose every surface is a square of same area.

Take an empty box with open top in the shape of a cube whose
each edge is 2 cm. Now fit cubes of edges 1 cm in it. From the figure it is
clear that 8 such cubes will fit in it. So the volume of the box will be equal
to the volume of 8 unit cubes together.

Therefore, the volume of the cube = 8 cu cm

Note that 8 = 2 × 2 × 2

Thus, volume of a cube = side × side × side = side^3

Hence, a cube has:

(i) six surfaces or faces,

(ii) 8 vertices,

(iii) 12 edges or sides of equal length.

Since a cube has all sides equal.

Volume of a cube = (side × side × side) cubic units.

= 1 × 1 × 1 cubic units

Since area = side × side

Volume of a cube = (area × side) cubic units.

Solved examples on volume of a cube:

1. Find the volume of a cube whose edge is 5 cm long.

The length of an edge = 5 cm

Volume of a cube = side of edge × side of edge × side of edge

Volume of a cube = 5 cm × 5 cm × 5 cm

= 125 cu cm

= 125 cm^3

2. Find the volume of a cube of side 7 cm.

We know, volume of a cube =(side × side × side) cubic units.

Here, side = 7 cm.

= 7 × 7 × 7

= 343

Therefore, volume of a cube = 343 cubic cm.

3. Find the volume of a cube of side 13 cm.

We know, volume of a cube =(side × side × side) cubic units.

Here, side = 13 cm.

= 13 × 13 × 13

= 2197

Therefore, volume of a cube = 2197 cubic cm.

4. Find the volume of water that can be contained in a cubical container each of whose edge measure 2 m internally.

The internal length of an edge of the container = 2 m

The internal volume of the container = 2 m × 2 m × 2 m = 8 cu m

The volume of water that the container can hold = the internal volume of the container.